PID (Partial Inversion Data): An M-of-N Level-Encoded Transition Signaling Protocol for Asynchronous Global Communication

A new delay-insensitive (DI) data encoding protocol for asynchronous global communication is proposed. It is an M-of-N Non-Return-to-Zero (NRZ) protocol and it is level-encoded, meaning that the decoding process simply uses the values of the codeword not their transitions. It has significant power and throughput benefits with respect to Return-to-Zero (RZ) codes, since no return-to-zero-phase is required. The proposed protocol also has a better (or equal) coding efficiency and it requires a similar decoding hardware as existing 1-of-N level-encoded NRZ codes (i.e., 1-of-2 LEDR and 1-of-N LETS), while it has worse (or equal) coding efficiency but requires significantly smaller decoding hardware than existing M-of-N transition-encoded NRZ codes. In particular, the 2-of-7 code, which encodes 4 data bits, completely dominates all other known DI NRZ codes since it has equal coding and power efficiency but less hardware overhead than transition-encoded ones, and it has equal power efficiency and hardware overhead but better coding efficiency than LETS.